Colours in OpenVDB volumes
The Principled Volume shader automatically picks up some details from attributes (eg, 'density' or 'temperature' and the Blackbody input can use this to generate the volume. This means it's not possible to change the Hue of the generated volume other than the Blackbody Tint - which effectively 'filters' the colours (multiply the RGB channels) - which loses some of the colour information.
The solution is to move the Blackbody colour generation outside of the shader and use the Emission sockets in place of Blackbody Intensity.
For a standard fire simulation this can be achieved with the following nodes :

Here the 'temperature' attribute node takes the place of the 'Temperature Attribute' in the Principled Volume node. The Multiply converts from the 0-1 range of the attribute into Kelvin (1.0 maps to 1000K) and the Blackbody generates the corresponding RGB values. The Hue Saturation node can be adjusted to change the hue without affecting the detail (change Hue from 0.5 to change the colour as desired).
Note that a maths node has been added to raise the 'flame' attribute to a power of 3. This seemed to be required to match the same intensity as that achieved when passing 'flame' directly into the Blackbody Intensity (presumably some conversion takes place within the Principled node itself).
You should be able to take this set up and replicate your results by using the 'density' in place of the 'flame' and/or 'temperature' attributes.
Here's an example of a standard Flame simulation with purple flame (Hue 0.2) to demonstrate the result :